1. Field of the Invention
The present invention relates to an apparatus and method for decoding one or more sequences of sub-word units output by a speech recognition system into one or more representative words.
2. Description of the Related Art
The use of speech recognition systems is becoming more and more popular due to the increased processing power available to perform the recognition operation. Most speech recognition systems can be classified into small vocabulary systems and large vocabulary systems. In small vocabulary systems the speech recognition engine usually compares the input speech to be recognised with acoustic patterns representative of the words known to the system. In the case of large vocabulary systems, it is not practical to store a word model for each word known to the system. Instead, the reference patterns usually represent phonemes of a given language. In this way, the input speech is compared with the phoneme patterns to generate one or more sequences of phonemes representative of the input speech. A word decoder is then used to identify possible words corresponding to the sequence or sequences of phonemes. Typically the decoding of the phoneme sequences into these word sequences is determined by comparing the phoneme sequences with Hidden Markov Models representative of the words using a lexicon.
The present invention aims to provide an alternative technique for decoding the phoneme sequences output by the recognition engine into one or more corresponding words.
According to one aspect, the present invention provides an apparatus for identifying one or more words corresponding to a sequence of sub-word units output by a recognition system in response to a rendition of the one or more words, the apparatus comprising means for receiving the recognized sequence of sub-word units representative of the one or more words to be recognized and for receiving a plurality of dictionary sub-word sequences each representative of one or more known words; means for comparing sub-word units of the recognized sequence with sub-word units of each dictionary sequence to provide a set of comparison results; and means for identifying the one or more words using the set of comparison results.